actually it was pretty common
It was basically like CoD Prestiges - every 100 levels you’d get a star under your icon, and after you completed the 5th star you’d start over but the icon would be a new “metal” ranging from Bronze to Diamond. It was just an indicator of playtime more than anything.
I had a … Platinum border I think… and whenever I was having a bad game in ranked someone would pull out the “LOL Plat border no-lifing this game and still stuck in Gold” card, usually by some wannabe smurf who wasn’t quite as good as they thought they were and wanted to blame anyone but themselves for losing.